Hydroshock inspection system

ABSTRACT

A method and apparatus for testing a test object. A stress wave is generated in a fluid within a cavity in a structure. The stress wave is directed through the fluid within the cavity into the test object.

BACKGROUND INFORMATION

1. Field

The present disclosure relates generally to testing objects and, inparticular, to testing the strength of bonds and objects. Still moreparticularly, the present disclosure relates to a method and apparatusfor testing the strength of bonds in a bonded structure using tensionwaves.

2. Background

A composite object may be comprised of one or more composite structuresthat are bonded to each other. The composite object is often required towithstand loads that may be encountered during normal or even abnormaluse of the composite object. As a result, identifying the strength ofbonds in the composite object nondestructively may be required to assessthat the composite object is capable of withstanding those forces.

Nondestructive testing or Non-destructive testing (NDT) is a wide groupof analysis techniques used in science and industry to evaluate theproperties of a material, component or system without causing damage.Because NDT does not permanently alter the article being inspected, itis a highly valuable technique that can save both money and time inproduct evaluation, troubleshooting and research.

Nondestructive testing of the composite object is more desirable. If thebonds in the composite object meet the desired standard, the compositeobject remains useable. Nondestructive evaluations are typicallyselected to fit specific bond material rather than general testing forall parameters. For example, laser bond inspection is a method currentlyused for nondestructive evaluations of bonds in composite objects. Laserbond inspection tests the strength of bonds between composite structureswithin a composite object. In this technique, weak bonds may be “pulledapart” by tension waves traveling through the structure. Existing bondinspection devices have multiple draw backs including the fact that theyare expensive to construct and operate, and their large footprint makesit difficult to inspect bonds with certain shapes.

Further, inspecting bonds on composite objects such as installed partson an aircraft may be more difficult than desired because of the sizeand limited reach of these types of laser bond inspection systems. Forexample, parts with narrow flanges or angles may preclude placement ofthe laser bond inspection head in a location to perform the inspection.

Therefore, it would be desirable to have a method and apparatus thattakes into account at least some of the issues discussed above, as wellas other possible issues.

SUMMARY

In one illustrative embodiment, a method for testing a test object ispresented. A stress wave is generated in a fluid within a cavity in astructure. The stress wave is directed through the fluid within thecavity into the test object.

In another illustrative embodiment, an apparatus comprises an energysource and a structure. The structure has a cavity configured to hold afluid. The energy source is configured to generate a stress wave thattravels through the fluid within the cavity into a test object.

The features and functions can be achieved independently in variousembodiments of the present disclosure or may be combined in yet otherembodiments in which further details can be seen with reference to thefollowing description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the illustrativeembodiments are set forth in the appended claims. The illustrativeembodiments, however, as well as a preferred mode of use, furtherobjectives and features thereof, will best be understood by reference tothe following detailed description of an illustrative embodiment of thepresent disclosure when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an illustration of an inspection environment in accordancewith an illustrative embodiment;

FIG. 2 is an illustration of a block diagram of an inspectionenvironment in accordance with an illustrative embodiment;

FIG. 3 is an illustration of a block diagram of an inspection unit inaccordance with an illustrative embodiment;

FIG. 4 is an illustration of a test setup in accordance with anillustrative embodiment;

FIG. 5 is an illustration of a cross-sectional view of a portion of aninspection environment in accordance with an illustrative embodiment;

FIG. 6 is an illustration of a wave generator in accordance with anillustrative embodiment;

FIG. 7 is an illustration of a cross-sectional view of a portion of awave generator in accordance with an illustrative embodiment;

FIG. 8 is an illustration of a wave generator in accordance with anillustrative embodiment;

FIG. 9 is an illustration of a cross-sectional view of a wave generatorin accordance with an illustrative embodiment;

FIG. 10 is an illustration of another cross-sectional view of a wavegenerator in accordance with an illustrative embodiment;

FIG. 11 is an illustration of a flowchart of a process for inspecting atest object in accordance with an illustrative embodiment;

FIG. 12 is an illustration of a flowchart of a process for testing atest object in accordance with an illustrative embodiment;

FIG. 13 is an illustration of a discharge of energy in a wave generatorin accordance with an illustrative embodiment;

FIG. 14 is an illustration of a block diagram of an aircraftmanufacturing and service method in accordance with an illustrativeembodiment; and

FIG. 15 is an illustration of a block diagram of an aircraft in which anillustrative embodiment may be implemented.

DETAILED DESCRIPTION

With laser bond inspection, a laser beam is directed at the frontsurface of a composite object. The laser beam creates mechanical wavesin the form of stress waves that travel through the composite objecttoward the back surface of the composite object. When the stress wavereaches a back surface of the object under test, the stress wave isreflected back from that surface producing a tension wave thatpropagates back toward the front surface of the object. The tensionwaves apply tension to the internal structure of the object, includingany bond lines between the front and back surface of the object. Thetension waves may have a sufficient strength that is selected todetermine whether bonds between the parts of the object have a desiredstrength.

Laser bond inspection may be considered a nondestructive testing methodwhen the bonds between composite structures are sufficiently strong. Ifa tension wave encounters a bond within the composite object that hasthe desired strength, the bond remains intact and inconsistencies areabsent. The composite object may be examined to determine whether anyinconsistencies are present in the composite object. If the bond issufficiently strong, the composite object is not altered and may be usedin different applications. This composite object also may be certifiedas providing a selected strength value.

If the tension wave encounters a bond within the composite object thatdoes not have the desired strength, an inconsistency may occur. If aninconsistency is present, the composite object does not have the desiredstrength and may be discarded, reworked, or otherwise processed.

Illustrative embodiments recognize and take into account one or moredifferent considerations. For example, those embodiments recognize andtake into account that stress waves may be generated using mechanismsother than a laser beam directed towards a test object. For example, theillustrative embodiments recognize and take into account that a stresswave may be generated through a fluid that is coupled to the testobject.

One or more of the illustrative embodiments may employ a hydroshocktechnique to generate a stress wave. In one illustrative example, astress wave is generated in a fluid within a cavity of a structure. Thestress wave is directed through the fluid and the cavity into a testobject. In one illustrative example, the structure with the cavity maytake the form of a tube or cylinder.

With reference now to the figures and in particular, with reference toFIG. 1, an illustration of an inspection environment is depicted inaccordance with an illustrative embodiment. Inspection environment 100is an example of one environment in which an illustrative embodiment maybe implemented.

In this illustrative example, fuselage 102 and skin panel 104 areexamples of composite objects. These composite objects may be comprisedof composite structures that are bonded to each other. In theseillustrative examples, an inspection of these bonds in fuselage 102 andskin panel 104 may be made in accordance with an illustrativeembodiment.

In this illustrative example, inspection system 106 is configured toinspect the bonds in fuselage 102 and skin panel 104. As depicted,inspection system 106 includes inspection unit 107, inspection unit 108,inspection unit 110, and computer 112.

In this illustrative example, inspection unit 107 is a portableinspection unit operated by operator 114. Operator 114 may placeinspection unit 107 at a location on skin panel 104. Operator 114 maythen move a distance away from inspection unit 107. This distance may bea distance that has been determined to be safe during operation ofinspection unit 107. Inspection unit 107 may then operate to performinspection of bonds within skin panel 104.

After the inspection of the bonds within skin panel 104 has taken placeat the location that inspection unit 107 was placed by operator 114,operator 114 may return to inspection unit 107 and move inspection unit107 to another location on skin panel 104.

In other illustrative examples, operator 114 may remain at the locationor may hold inspection unit 107 during inspection of the bonds withinskin panel 104 depending on the amount of energy generated by inspectionunit 107 and the design of inspection unit 107. A more detailedillustration of inspection unit 107 in section 115 is found in thedescription of FIG. 4 below.

Inspection unit 108 takes the form of an end effector for robotic arm116. Robotic arm 116 may move inspection unit 108 along fuselage 102 toperform inspections of bonds within fuselage 102.

As depicted, inspection unit 110 takes the form of a crawler. Inspectionunit 110 may move on fuselage 102 to perform inspections of bonds withinfuselage 102.

Information generated by inspection unit 107, inspection unit 108, andinspection unit 110 are sent to computer 112. Initially, computer 112may send commands to inspection unit 107, inspection unit 108, andinspection unit 110 to control the operation of these inspection units.The information and commands are sent over communications link 118,communications link 120, and communications link 122 in thisillustrative example. As depicted, communications link 118 is a wiredcommunications link. Communications link 120 and communications link 122are wireless communications links.

The illustration of inspection environment 100 is only provided as anexample of one type of environment in which an illustrative embodimentmay be used to test bonds. One or more illustrative embodiments may beimplemented in inspection environment 100 to inspect other types ofobjects other than aircraft parts. For example, the illustrativeembodiments may be applied to testing bonds in a test object that may beselected from one of parts for an automobile, a building, a completedaircraft, a part installed on an aircraft, and other suitable types ofobjects that may contain bonds for which testing is desirable.

Turning next to FIG. 2, an illustration of a block diagram of aninspection environment is depicted in accordance with an illustrativeembodiment. Inspection environment 100 in FIG. 1 is an example of oneimplementation for inspection environment 200 shown in block form inFIG. 2.

As depicted, inspection environment 200 includes inspection system 202.Inspection system 202 is configured to test object 204. In particular,inspection system 202 is configured to test bond 206 in test object 204.

In this illustrative example, bond 206 is present where first structure208 and second structure 210 are bonded to each other at bond line 212.Bond line 212 may be planar, nonplanar, or some combination thereofdepending on the particular implementation.

In these illustrative examples, first structure 208 and second structure210 may be bonded to each other in a number of different ways. Forexample, first structure 208 and second structure 210 may be bonded toeach other using an adhesive.

Test object 204 may be comprised of any type of material. As depicted,test object 204 is composite object 214 in this illustrative example.Further, first structure 208 is first composite structure 216, andsecond structure 210 is second composite structure 218.

In this illustrative example, inspection system 202 includes computersystem 220, display system 224, and group of inspection units 226. Asused herein, a “group of,” when used with reference items, means one ormore items. For example, group of inspection units 226 is one or moreinspection units.

Computer system 220 is configured to control the operation of group ofinspection units 226. Computer system 220 is one or more computers. Whenmore than one computer is present in computer system 220, thosecomputers may communicate with each other using a communications mediumsuch as a network.

In this illustrative example, stress wave 228 is generated by inspectionunit 230 in group of inspection units 226 and directed into test object204. In the illustrative example, stress wave 228 is a wave that has acompressive component. Additionally, stress wave 228 also may have atensile component at the tail or end of the wave.

Inspection unit 230 is a hardware system in these illustrative examples.In the illustrative examples, stress wave 228 generates a force on testobject 204.

Tension wave 232 is generated either as a part of stress wave 228 orwhen the compressive component of stress wave 228 encounters a boundaryin test object 204. This boundary may be, for example, the back wall ofthe test object 204 or some other suitable interface that may be withintest object 204. Tension wave 232 generates a force that applies tensionto the internal structure of test object 204. For example, tension wave232 may pull at least one of first structure 208 and second structure210 away from each other at bond line 212. Tension wave 232 may resultin a load that is applied to bond 206. In the illustrative example, thisload may be localized. The load may be considered to be localized whenthe load is applied to a specific area of the test object. In otherwords, the load maybe applied to an area rather than spread outthroughout the test object.

As depicted, inspection unit 230 is also configured to measure at leastone of stress wave 228 and tension wave 232 in test object 204. As usedherein, the phrase “at least one of,” when used with a list of items,means different combinations of one or more of the listed items may beused and only one of each item in the list may be needed. For example,“at least one of item A, item B, or item C” may include, withoutlimitation, item A or item A and item B. This example also may includeitem A, item B, and item C or item B and item C. In other examples, “atleast one of” may be, for example, without limitation, two of item A,one of item B, and ten of item C; four of item B and seven of item C;and other suitable combinations. The item may be a particular object,thing, or a category. In other words, at least one of means anycombination items and number of items may be used from the list but notall of the items in the list are required.

After stress wave 228 has been directed into test object 204 and tensionwave 232 has traveled through test object 204, inspection unit 230 maymake measurements 236 of test object 204. Inspection unit 230 maymeasure at least one of wave energy, front surface displacement orvelocity, back-surface displacement or velocity, ultrasonictransmission, ultrasonic attenuation, and other suitable properties withrespect to test object 204.

Inspection unit 230 may send measurements 236 made of test object 204after stress wave 228 and tension wave 232 have traveled through testobject 204 to computer system 220 for storage. As depicted, computersystem 220 may store at least one of information 238 and measurements236. In other illustrative examples, inspection unit 230 may storeinformation 238, measurements 236, or both.

Display system 224 is a hardware system and may include one or moredisplay devices. Display system 224 may be connected to computer system220, inspection unit 230, or both of these systems. Display system 224is configured to display information 238. Information 238 is based onmeasurements 236 of test object 204. In these illustrative examples,display system 224 may be, for example, selected from one of anoscilloscope, a tablet computer, a notebook computer, and a workstation.

With reference next to FIG. 3, an illustration of an inspection unit isdepicted in accordance with an illustrative embodiment. In this depictedexample, an example of components that may be found in inspection unit230 in FIG. 2 is shown.

In this illustrative example, inspection unit 230 comprises a number ofdifferent components. In this depicted example, inspection unit 230includes wave generator 314 and measurement system 312.

In this illustrative example, wave generator 314 in inspection unit 230includes a number of different components. For example, wave generatorin inspection unit 230 includes structure 300, cavity 302, and energysource 304.

Structure 300 may be any structure in which cavity 302 is configured tohold fluid 306 within cavity 302. Structure 300 may be comprised of anysuitable material. For example, structure 300 may be comprised of ametal, plastic, titanium, steel, aluminum, polycarbonate, and othersuitable materials.

In the illustrative example, structure 300 with cavity 302 hasconfiguration 308. As depicted, cavity 302 is configured to directstress wave 228 through fluid 306 in cavity 302 into test object 204 inFIG. 2. Fluid 306 may take various forms. For example, fluid 306 may bewater, oil, and other suitable types of fluids.

Additionally, configuration 308 is selected to set number of properties310 for stress wave 228. Number of properties 310 for stress wave 228 isset as stress wave 228 travels through cavity 302 into test object 204.As used herein, “a number of,” when used with reference to items, meansone or more items. For example, number of properties 310 is one or moreproperties. In the illustrative example, number of properties 310 isselected from at least one of a magnitude of stress wave 228, durationof stress wave 228, a rise time for stress wave 228, and the depth atwhich stress wave 228 is focused in the test object.

Measurement system 312 is a hardware system and is configured to measureat least one of stress wave 228 and tension wave 232 in test object 204in FIG. 2. Measurement system 312 may take various forms. For example,measurement system 312 may be selected from at least one of a laserinterferometer, a transducer system, and other suitable types of systemsthat may measure at least one of stress wave 228 and tension wave 232while those waves travel within test object 204 in FIG. 2. Themeasurements may be surface displacements, surface velocities orinternal material changes.

As depicted, wave generator 314 and measurement system 312 may beassociated with platform 318. Platform 318 may take various forms suchas a housing, a frame, an end effector, a crawler, or some othersuitable type of platform. Of course, in some illustrative examples,wave generator 314 and measurement system 312 may be separatecomponents.

The illustration of inspection environment 200 and the differentcomponents in FIGS. 2-3 are not meant to imply physical or architecturallimitations to the manner in which an illustrative embodiment may beimplemented. Other components in addition to or in place of the onesillustrated may be used. Some components may be unnecessary. Also, theblocks are presented to illustrate some functional components. One ormore of these blocks may be combined, divided, or combined and dividedinto different blocks when implemented in an illustrative embodiment.

For example, although only bond 206 is illustrated in the example ininspection environment 200 in FIG. 2, one or more additional bonds maybe present in addition to or in place of bond 206. Further, test object204 also may include one or more additional structures in addition tofirst structure 208 and second structure 210. These additionalstructures may or may not be composite structures depending on theparticular implementation.

As another illustrative example, in some illustrative examples,measurement system 312 may be a separate component outside of inspectionunit 230. In still other illustrative examples, the controller orprocessor also may be part of inspection unit 230. In yet anotherillustrative example, display system 224 may be included as part ofinspection unit 230 in FIG. 2.

Turning now to FIG. 4, an illustration of a test setup is depicted inaccordance with an illustrative embodiment. In this depicted example, amore detailed illustration of inspection unit 107 operated by operator114 from FIG. 1 is shown.

Also depicted in this view, inspection unit 107 includes a number ofdifferent components. For example, in inspection environment 400,inspection unit 107 includes frame 401, wave generator 402, andmeasurement unit 404.

As depicted, frame 401 is an example of one implementation for platform318 shown in block form in FIG. 3. Frame 401 is a portable frame. Frame401 may be moved from location to location by operator 114 to inspectskin panel 104.

Wave generator 402 and measurement unit 404 are associated with frame401. When one component is “associated” with another component, theassociation is a physical association in the depicted examples. Forexample, a first component, wave generator 402, may be considered to beassociated with a second component, frame 401, by being secured to thesecond component, bonded to the second component, mounted to the secondcomponent, welded to the second component, fastened to the secondcomponent, and/or connected to the second component in some othersuitable manner. The first component also may be connected to the secondcomponent using a third component. The first component may also beconsidered to be associated with the second component by being formed aspart of and/or an extension of the second component.

In this view, tube 406 and energy source 408 are shown. As depicted,tube 406 has a shape of a frustrum. Tube 406 is an example of a physicalimplementation for structure 300 shown in block form in FIG. 3.Additionally, tube 406 has first end 410 and second end 412.

Energy source 408 is configured to generate a stress wave. Energy source408 is associated with first end 410. Second end 412 is configured to beplaced on surface 414 of skin panel 104 in this illustrative example.

As depicted, measurement unit 404 is hardware and is configured to makemeasurements of waves within skin panel 104 that are generated by wavegenerator 402. Measurement unit 404 is an example of a physicalimplementation of measurement system 312 shown in block form in FIG. 3.In this illustrative example, measurement unit 404 takes the form of alaser interferometer 416.

As can be seen in this view, skin panel 104 is comprised of firstcomposite structure 418 and second composite structure 420. These twocomposite structures are bonded to each other at bond line 422 in thisillustrative example. Inspection unit 107 is used to test the bondbetween first composite structure 418 and second composite structure420.

With reference now to FIG. 5, an illustration of a cross-sectional viewof a portion of an inspection environment is depicted in accordance withan illustrative embodiment. In this illustrative example, across-sectional view of some components in inspection environment 400 inFIG. 4 is seen taken along lines 5-5.

In this cross-sectional view, cavity 500 of tube 406 is shown. Cavity500 is an example of a physical implementation for cavity 302 shown inblock form in FIG. 3. As can be seen, fluid 502 is present in cavity500. In this example, fluid 502 takes the form of water. Of course,other types of fluids may be used depending on the particularimplementation.

As depicted, plug 503 is associated with second end 412. Plug 503 is astructure that is configured to hold fluid 502 within cavity 500 whensecond end 412 of tube 406 is placed against surface 414 of skin panel104. In these illustrative examples, plug 503 may take various forms. Asdepicted, plug 503 seals second end 412. In other illustrative examples,plug 503 may be a gasket that generates a seal when second end 412 isplaced against surface 414 of skin panel 104.

In this illustrative example, energy source 408 is a hardware device andis configured to generate stress wave 506. In these illustrativeexamples, energy source 408 may generate energy in the form of anexplosion or shockwave for a duration that is short enough to causestress wave 506. In this illustrative example, energy source 408includes capacitor 504. As depicted, capacitor 504 is in contact withfluid 502.

When capacitor 504 is discharged, the energy from the discharge resultsin the generation of stress wave 506. Stress wave 506 travels throughfluid 502 within cavity 500 into the test object, which is skin panel104 in this illustrative example. When plug 503 seals cavity 500, plug503 also may function as a coupler for stress wave 506. When plug 503performs this function, the selection of materials for plug 503 may beselected to have an acoustic impedance close to tube 406. In otherwords, the selection of the material and shape of plug 503 may beselected to reduce reflection of stress wave 506.

In this illustrative example, stress wave 506 travels through skin panel104 until stress wave 506 reaches a feature. In this illustrativeexample, the feature is back surface 508. At back surface 508, tensionwave 510 occurs during reflection of stress wave 506. Tension wave 510subjects bond 421 at bond line 422 to tensile stress in thisillustrative example. In other words, tension wave 510 causes tensionthat pulls first composite structure 418 and second composite structure420 away from each other.

In this illustrative example, the configuration of tube 406 with cavity500 is selected to set properties for stress wave 506. For example, theshape of tube 406 may be designed to focus the wave at a desired depthwithin skin panel 104, such as at the depth where bond 421 is located.This wave may be at least one of a stress wave or a tensile wave. Thisfocusing of the wave may optimize the inspection method by maximizingthe stress at the location of interest, reducing the likelihood ofunintended occurrences of undesired inconsistencies to the test objectin regions away from the bond to be inspected.

In this illustrative example, wave generator 402 has height 513. Wavegenerator 402 has width 514 at first end 410 and width 516 at second end412. As depicted, height 513 may be about several centimeters, width 514may be about a few centimeters, and width 516 may be about 1 centimeter.Of course these dimensions may vary depending on the particularimplementation. The dimension selected may vary depending on theparticular implementation. In these illustrative examples, dimensionsmay be selected such that wave generator 402 may be easily positioned ondifferent parts to provide a desired inspection of bonds in those parts.

Turning now to FIG. 6, an illustration of a wave generator is depictedin accordance with an illustrative embodiment. As depicted, wavegenerator 600 is another example of an implementation for wave generator314 shown in block form in FIG. 3. Wave generator 600 comprisesstructure 602 having a cylindrical shape rather than a tube as depictedfor wave generator 402 in FIG. 4.

In this illustrative example, cavity 604 can be seen in phantom withinstructure 602. As can be seen in this example, cavity 604 has an eggshape. This configuration of structure 602 is another example of anotherphysical implementation for cavity 302 shown in block form in FIG. 3.

Wire 606 extends through structure 602 into cavity 604. Wire 606 isconnected to wire 608 and wire 610. Wire 608 and wire 610 are thickerthan wire 606. Wire 606 is an example of an implementation for energysource 304 shown in block form in FIG. 3. Wire 606 is an explodingbridge wire which explodes when a current flows through wire 606. Thisexplosion is configured to generate a stress wave in a fluid withincavity 604.

Also shown in phantom is gasket 612. Gasket 612 is configured to sealcavity 604 at end 614 of cavity 604.

As depicted, structure 602 has height 616 and diameter 618. Height 616may be about 3.7 centimeters, and diameter 618 may be about 7centimeters in this illustrative example.

With reference now to FIG. 7, an illustration of a cross-sectional viewof a portion of wave generator 600 is depicted in accordance with anillustrative embodiment. A larger view of cavity 604, wire 606, andgasket 612 can be seen. In particular, end 614 of cavity 604 hasdiameter 700. Diameter 700 is about 1 centimeter in this illustrativeexample.

Turning now to FIG. 8, an illustration of a wave generator is depictedin accordance with an illustrative embodiment. In this illustrativeexample, wave generator 800 is another example of a physicalimplementation for wave generator 314 shown in block form in FIG. 3.

In this illustrative example, wave generator 800 has structure 801.Structure 801 has a cuboid shape. In this particular example, structure801 has height 802, depth 804, and width 806. In this illustrativeexample, height 802 is about 1 centimeter, depth 804 is about 2centimeters, and width 806 is about 2 centimeters. Of course, the valuesfor these dimensions are only examples of one set of dimensions forheight 802, depth 804, and width 806. Other values for these dimensionsmay be used in other illustrative implementations.

Turning next to FIG. 9, an illustration of a cross-sectional view of awave generator is depicted in accordance with an illustrativeembodiment. In this illustrative example, a cross-sectional view ofstructure 801 is shown taken along lines 9-9 in FIG. 8.

In this illustrative example, cavity 900 has a conical shape. Energysource 902 takes the form of wire 904. Wire 904 is configured to explodewhen a current is applied to wire 904. This explosion is configured togenerate a stress wave in a fluid within cavity 900.

With reference now to FIG. 10, an illustration of anothercross-sectional view of a wave generator is depicted in accordance withan illustrative embodiment. In this illustrative example, an alternatecross-sectional view of structure 801 is shown taken along lines 10-10.

In this cross-sectional view, cavity 1000 has a hemispherical shape.Energy source 1001 is wire 1002 in this example.

The different components shown in FIG. 1 and FIGS. 4-10 may be combinedwith components in FIGS. 2-3, used with components in FIGS. 2-3, or acombination of the two. Additionally, some of the components in FIG. 1and FIGS. 4-10 may be illustrative examples of how components shown inblock form in FIGS. 2-3 can be implemented as physical structures.

Turning next to FIG. 11, an illustration of a flowchart of a process forinspecting a test object is depicted in accordance with an illustrativeembodiment. The process illustrated in FIG. 11 may be implemented ininspection environment 200 in FIG. 2. In particular, the process may beimplemented to inspect test object 204 using inspection unit 230.

The process begins by placing the inspection unit on a surface of thetest object (operation 1100). The process then generates a stress wavein a fluid within a cavity of a structure (operation 1102). The processthen directs the stress wave through the fluid and the cavity into thetest object (operation 1104). A number of properties for the stress wavein the fluid is set based on the configuration of the cavity in thestructure. These properties are set as the stress wave travels throughthe fluid in the cavity. As a result, the stress wave causes a tensionwave that encounters a bond in the test object. In the illustrativeexample, the tension wave that encounters the test object may be thetension wave caused by the stress wave reflecting from an interface suchas a back wall. Further, in some illustrative examples, the tension wavealso may be a component of the stress wave that encounters the bond asthe stress wave travels towards the interface.

Measurements are made of the test object (operation 1106). In operation1106, the measurements may be performed using any device configured todetect inconsistencies that may occur from the bond carrying the loadcaused by the tensile forces that may be applied by the tension wave. Inone illustrative example, a laser interferometer is used to determinewhether inconsistencies are present after the stress wave travelsthrough the test object and causes a tension wave to apply a load on thebond. Information based on measuring the test object is displayed(operation 1108). The process also stores at least one of theinformation and the measurements (operation 1110), with the processterminating thereafter.

These operations may be used to determine whether the bond in the testobject can withstand loads within a desired amount or range. Thesedifferent operations may be repeated any number of times. The operationsmay be repeated for different locations on a particular test object oron different test objects.

With reference now to FIG. 12, an illustration of a flowchart of aprocess for testing a test object is depicted in accordance with anillustrative embodiment. This process may be implemented after a tensionwave has been sent through a test object. The process illustrated inFIG. 12 may be implemented using inspection system 202 in FIG. 2.

The process begins by sending a number of signals into the test object(operation 1200). These signals may be sent using an ultrasonictransducer.

The process then detects response signals (operation 1202). Adetermination is then made as to whether the response signals indicatethat an inconsistency is present in the test object (operation 1204). Ifan inconsistency is present, an indication is generated that the testobject failed the test (operation 1206), with the process terminatingthereafter.

With reference again to operation 1204, if an inconsistency is notpresent, the process generates an indication that the test object haspassed the test (operation 1208), with the process terminatingthereafter. In this case, the bond in the test object has held up to theforces generated on the bond by the tension waves. As a result, thistest object may be certified as withstanding the force selected fortesting.

The flowcharts and block diagrams in the different depicted embodimentsillustrate the architecture, functionality, and operation of somepossible implementations of apparatuses and methods in an illustrativeembodiment. In this regard, each block in the flowcharts or blockdiagrams may represent a module, a segment, a function, and/or a portionof an operation or step. For example, one or more of the blocks may beimplemented as program code, in hardware, or a combination of theprogram code and hardware. When implemented in hardware, the hardwaremay, for example, take the form of integrated circuits that aremanufactured or configured to perform one or more operations in theflowcharts or block diagrams. When implemented as a combination ofprogram code and hardware, the implementation may take the form offirmware.

In some alternative implementations of an illustrative embodiment, thefunction or functions noted in the blocks may occur out of the ordernoted in the figures. For example, in some cases, two blocks shown insuccession may be executed substantially concurrently, or the blocks maysometimes be performed in the reverse order, depending upon thefunctionality involved. Also, other blocks may be added in addition tothe illustrated blocks in a flowchart or block diagram.

For example, operation 1108 and operation 1110 are optional operationsand may be omitted. Further, in other illustrative examples, an alertmay be generated if a determination is made from the measurement of thedifferent waves that the bond does not have a desired strength.Additionally, other types of measurement systems may be used dependingon the particular implementation.

Turning now to FIG. 13, an illustration of a discharge of energy in awave generator is depicted in accordance with an illustrativeembodiment. In this illustrative example, graph 1300 illustrates shape1302 of a stress wave that is discharged into fluid 1304. This stress isshown at a time of about 3.05×10 006 seconds after energy discharge.

Graph 1306 shows the stress in Gdyn/cm². In this illustrative example, 1Gdyn/cm² is a measure of stress equivalent to 1 kilobar, or 1000 atm. Ascan be seen, the stress wave generated may be focused at a specificdepth in a test object based on the configuration of the cavity. Byvarying the shape of the cavity, the focal point of the stress wave maybe changed. This focal point may be at different locations such as at aninterface, a back wall of an object, the bond line, or some otherlocation depending on the particular implementation. The depth of thefocal point may be selected to provide a desired testing of the bondline.

Illustrative embodiments of the disclosure may be described in thecontext of aircraft manufacturing and service method 1400 as shown inFIG. 14 and aircraft 1500 as shown in FIG. 15. Turning first to FIG. 14,an illustration of a block diagram of an aircraft manufacturing andservice method is depicted in accordance with an illustrativeembodiment. During pre-production, aircraft manufacturing and servicemethod 1400 may include specification and design 1402 of aircraft 1500in FIG. 15 and material procurement 1404.

During production, component and subassembly manufacturing 1406 andsystem integration 1408 of aircraft 1500 in FIG. 15 takes place.Thereafter, aircraft 1500 in FIG. 15 may go through certification anddelivery 1410 in order to be placed in service 1412. While in service1412 by a customer, aircraft 1500 in FIG. 15 is scheduled for routinemaintenance and service 1414, which may include modification,reconfiguration, refurbishment, and other maintenance or service.

Each of the processes of aircraft manufacturing and service method 1400may be performed or carried out by a system integrator, a third party,and/or an operator. In these examples, the operator may be a customer.For the purposes of this description, a system integrator may include,without limitation, any number of aircraft manufacturers andmajor-system subcontractors; a third party may include, withoutlimitation, any number of vendors, subcontractors, and suppliers; and anoperator may be an airline, a leasing company, a military entity, aservice organization, and so on.

With reference now to FIG. 15, an illustration of a block diagram of anaircraft is depicted in which an illustrative embodiment may beimplemented. In this example, aircraft 1500 is produced by aircraftmanufacturing and service method 1400 in FIG. 14 and may includeairframe 1502 with systems 1504 and interior 1506. Examples of systems1504 include one or more of propulsion system 1508, electrical system1510, hydraulic system 1512, and environmental system 1514. Any numberof other systems may be included. Although an aerospace example isshown, different illustrative embodiments may be applied to otherindustries, such as the automotive industry.

Apparatuses and methods embodied herein may be employed during at leastone of the stages of aircraft manufacturing and service method 1400 inFIG. 14.

For example, the illustrative embodiments may be implemented to inspectthe bonds in test objects such as aircraft parts during component andsubassembly manufacturing 1406. Further, different parts may be testedusing an illustrative embodiment after or during installation of thoseparts as part of system integration 1408. Further tests of parts may bemade during certification and delivery 1410. As another illustrativeexample, parts may be tested during maintenance and service 1414. Thistesting may be performed on parts that may be inspected duringmaintenance and service 1414. Further, parts may be tested using anillustrative embodiment for use in maintenance, upgrades, refurbishment,or other operations performed during maintenance and service 1414.

Thus, the illustrative embodiments provide a method and apparatus fortesting bonds in objects. In these illustrative examples, the wavegenerator may have a size that is smaller than currently used ininspection systems such as laser bond inspection systems. The size ofthe wave generator in these illustrative examples may allow for testingof parts that have configurations or shapes that are more difficult forinspection with laser bond inspection systems. Further, the size of thewave generator in these illustrative examples may allow for inspectionsof objects, such as parts that have been installed in a structure suchas an aircraft, a train, a building, a manufacturing facility, or someother type of structure.

The illustrative embodiments allow for the stress wave to have a numberof properties such as magnitude of the stress wave, duration of thestress wave, a rise time for the stress wave, a focal point, and othersuitable properties that may be set based on the configuration of thewave generator. In this manner, the different illustrative embodimentsprovide that wave generators may be used to test various bond strengthsfor bonds that may be in different locations in a test object.

The description of the different illustrative embodiments has beenpresented for purposes of illustration and description and is notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different illustrativeembodiments may provide different features as compared to otherillustrative embodiments. The embodiment or embodiments selected arechosen and described in order to best explain the principles of theembodiments, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed is:
 1. A method for testing a test object, the methodcomprising: generating, via a wire at a first end of a structure, astress wave within a cavity in the structure, wherein a surface of thetest object is coupled to a second end of the structure opposite thefirst end of the structure, and wherein the wire is an exploding bridgeconfigured to explode when a current flows through the wire; setting anumber of properties for the stress wave in a fluid within the cavitybased on a configuration of the cavity, wherein the number of propertiescomprise a depth within the test object from the surface of the testobject at which the stress wave is focused in the test object; anddirecting the stress wave through the cavity into the test object to thedepth within the test object.
 2. The method of claim 1, wherein thenumber of properties further comprises a magnitude of the stress wave, aduration of the stress wave, or a rise time for the stress wave.
 3. Themethod of claim 1, wherein the directing step comprises: directing thestress wave through a fluid within the cavity into the test object,wherein a tension wave occurs and encounters a bond in the test object.4. The method of claim 3 further comprising: measuring the test object.5. The method of claim 4 further comprising: displaying informationbased on measurements of the test object.
 6. The method of claim 4further comprising: storing at least one of information or measurementsof the test object.
 7. The method of claim 1, wherein the structure is atube having the first end and the second end.
 8. The method of claim 1,wherein the cavity is filled with the fluid, and the stress wave isgenerated by a hydroshock technique.
 9. The method of claim 1, whereinthe cavity has a cross-sectional shape of a cone.
 10. An apparatuscomprising: an energy source comprising a wire at a first end of astructure, wherein the wire is an exploding bridge configured to explodewhen a current flows through the wire; and the structure having acavity, wherein the energy source is configured to generate a stresswave that travels through the cavity into a test object having a surfacecoupled to a second end of the structure opposite the first end of thestructure, wherein the structure is configured to set a number ofproperties for the stress wave in a fluid within the cavity based on aconfiguration of the cavity in the structure, and wherein the number ofproperties comprises a depth within the test object from the surface ofthe test object at which the stress wave is focused in the test object.11. The apparatus of claim 10, wherein the number of properties furthercomprises a magnitude of the stress wave, a duration of the stress wave,or a rise time for the stress wave.
 12. The apparatus of claim 10,wherein the structure is configured to direct the stress wave throughthe fluid within the cavity into the test object such that a tensionwave occurs and encounters a bond in the test object.
 13. The apparatusof claim 10 further comprising: a measurement system configured tomeasure the test object.
 14. The apparatus of claim 13, wherein themeasurement system comprises: a laser interferometer.
 15. The apparatusof claim 13, wherein the measurement system is configured to store atleast one of information or measurements of the test object.
 16. Theapparatus of claim 13 further comprising: a display system configured todisplay information about the test object measured by the measurementsystem.
 17. The apparatus of claim 16, wherein the display system isselected from one of an oscilloscope, a tablet computer, a notebookcomputer, or a workstation.
 18. The apparatus of claim 10, wherein thestructure comprises: a tube having the first end and the second end. 19.The apparatus of claim 18 further comprising: a plug configured to beassociated with the second end and to hold the fluid within the cavity.